Media handing devices process media documents and bunches of media documents after separating the media documents for individual processing downstream within the media handling devices. Media handing devices include a variety of integrated components. One type of media document is a banknote or currency note (note).
As the note is processed through the media handling device, a variety of sensors are activated and deactivated to track movement of the note and indicate where the note is located along the transport pathway.
Typically, track sensors or photodiode (emitter) and phototransistor pairs, located on the same or opposing sides of the document track are activated before and/or after media handling components for purposes of transmitting a presence of the note on the track as signals to integrated controllers within the media handling devices.
Depending on the location of a note along the pathway, other devices may be activated, such as a media validation module (device) located in a designated area along the pathway. The media validation module may include cameras, sensors (Infrared, Ultraviolet (UV), etc.) and Light Emitting Diodes (LEDs) that illuminate the face of the note to capture different characteristics of the note for purposes of determining whether the note is counterfeit (fake) or unfit in some manner (excessively damaged).
The security features of a note generally fall into two categories: those associated with the printing process and those resident in the substrate. In terms of automatic validation, it is an attainable task to examine the printing feature through multi-spectrum of imaging, but the validation of substrate feature is a long-standing challenge because there does not exist such an instrument capable of measuring the middle part of a media. Existing solutions rely mostly on transmissive images, but in a transmissive image the substrate signal is submerged by the rich information of the two-sided printing details.
The weakness in examining substrate features is an un-ignorable drawback to automatic banknote processing systems, which is exposed to the risk of accepting counterfeits. One challenge of these test notes is their printing features are perfectly reproduced whereas some substrate features are omitted.